How does this medication work? What will it do for me?

Fluoxetine belongs to a class of medications called selective serotonin reuptake inhibitors (SSRIs). It is used for the treatment of depression and helps to elevate mood. Fluoxetine is also used to reduce or eliminate the symptoms of obsessive-compulsive disorder (OCD) as well as to treat the eating disorder, bulimia nervosa.

Selective serotonin reuptake inhibitors work by increasing the amount of a neurotransmitter, called serotonin, which is available in certain parts of the brain. Although you may start feeling better within a few weeks of treatment, the full effects of the medication may not be evident until several weeks of treatment have passed.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

How should I use this medication?

To treat depression, the recommended starting dose of fluoxetine for adults is 20 mg. After several weeks, your doctor may advise you to increase the dose if your symptoms have not improved. The maximum recommended dose of fluoxetine is 60 mg daily. Once your symptoms have been brought under control, the lowest effective dose of fluoxetine as prescribed by your doctor should be used to keep the symptoms from coming back. Your doctor may advise you to keep taking fluoxetine for several months.

For the eating disorder bulimia nervosa, the recommended adult dosage is 60 mg taken daily, although lower doses may be effective.

The recommended dose of fluoxetine to treat obsessive-compulsive disorder ranges from 20 mg to 60 mg taken once daily.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

Fluoxetine is generally taken once daily, in the morning. It may be taken with food or on an empty stomach.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as you remember. If it is almost time for the next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take fluoxetine if you:

are allergic to fluoxetine or any ingredients of the medication

have taken a MAO inhibitor (e.g., phenelzine, tranylcypromine) or thioridazine within the past 14 days

Do not take MAO inhibitors or thioridazine until at least 5 weeks after you stop your treatment with fluoxetine.

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

anxiety

decreased appetite

decreased sexual ability or drive

diarrhea

dizziness

drowsiness

dry mouth

headache

increased sweating

nausea

nervousness

symptoms of hypoglycemia (low blood sugar), including:

anxiety or nervousness

chills

cold sweats

confusion

cool, pale skin

difficulty concentrating

drowsiness

excessive hunger

fast heartbeat

headache

shakiness or unsteady walk

unusual tiredness or weakness

tiredness

trouble sleeping

upset stomach

weakness

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

symptoms of increased pressure in the eyes (e.g., decreased or blurred vision, eye pain, red eye, swelling of the eye)

talking, feeling, and acting with excitement and activity you cannot control

unusual or incomplete body or facial movements

unusual secretion of milk (women)

Stop taking the medication and seek immediate medical attention if any of the following occur:

convulsions (seizures)

signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)

signs of bleeding in the stomach (e.g., bloody, black, or tarry stools, spitting up of blood, vomiting blood or material that looks like coffee grounds)

symptoms of hyponatremia (low blood sodium), including:

confusion

convulsions (seizures)

drowsiness

dryness of mouth

increased thirst

lack of energy

symptoms of serotonin syndrome, including:

diarrhea

fever

increased sweating

mood or behaviour changes

overactive reflexes

racing heartbeat

restlessness

shivering or shaking

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Allergy: Approximately 7% of people who take fluoxetine develop a rash or hives. Almost one third of these people need to stop treatment because of the rash. If you get a skin rash while taking this medication, consult your doctor as soon as possible.

Bleeding: Fluoxetine may cause a reduced number of platelets in the blood, which can make it difficult to stop cuts from bleeding. If you notice any signs of bleeding, such as frequent nosebleeds, unexplained bruising, or black and tarry stools, notify your doctor as soon as possible. Your doctor will order routine blood tests to make sure potential problems are caught early.

Bone Health: Fluoxetine, like other SSRI medications, may increase the risk of bone fracture, especially if you are a senior or have osteoporosis or other major risk factors for breaking a bone. Take extra care to avoid falls, especially if you get dizzy or have low blood pressure. Your doctor may monitor your bones while you are taking this medication.

Diabetes: Fluoxetine may cause changes in blood glucose control. If you have diabetes, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Your doctor may want you to monitor your blood sugar more carefully while you are taking fluoxetine.

Drowsiness/reduced alertness: Fluoxetine may cause drowsiness or dizziness, affecting your ability to drive or operate machinery. Avoid these and other hazardous tasks until you have determined how this medication affects you.

Glaucoma: This medication may cause the symptoms of glaucoma (increased pressure in the eye) to become worse. If you have glaucoma, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Report any changes in vision to your doctor as soon as possible while you are taking this medication.

Heart rhythm: Fluoxetine can cause changes to the normal rhythm of the heart, including an irregular heartbeat called QT prolongation. QT prolongation is a serious life-threatening condition that can cause fainting, seizures, and sudden death. If you are at risk for heart rhythm problems (e.g., people with heart failure, angina, low potassium or magnesium levels), discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Kidney function: Severe kidney disease may affect how fluoxetine is removed from the body and contribute to side effects. If you have reduced kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: Liver disease or reduced liver function may cause this medication to build up in the body, causing side effects. If you have liver problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Your doctor may want to test your liver function regularly with blood tests while you are taking this medication.

If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Low sodium levels: This medication may cause low sodium levels, especially for seniors, people who are dehydrated, and people taking diuretics (water pills). Contact your doctor if you notice symptoms of low sodium such as confusion, concentration or memory problems, weakness, or unsteadiness.

Psychiatric Conditions: Fluoxetine has been reported to cause manic episodes, particularly for people who have bipolar disorder. Signs of mania include extreme levels of energy, hallucinations, suspiciousness, aggression or difficulty focusing your thoughts. If you experience any of these, or if you notice these signs in a family member who is taking fluoxetine, contact your doctor immediately. You should be closely monitored by your doctor for emotional and behaviour changes while taking this medication.

Seizures: There have been occasional reports of seizures occurring with fluoxetine. Seizures are more likely to occur when higher doses of this medication are taken. If you have a history of epilepsy or medical conditions that increase the risk of seizures, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Serotonin Syndrome/ Neuroleptic Malignant Syndrome : Severe reactions are possible when fluoxetine is combined with other medications that act on serotonin, such as tricyclic antidepressants and certain medications for migraine headache. Symptoms of a reaction may include muscle rigidity and spasms, difficulty moving, changes in mental state including delirium and agitation. Coma and death are possible.

If you are taking other medications, discuss with your doctor how these medications may affect your medical condition, how your medical condition may affect the dosing and effectiveness of these medications, and whether any special monitoring is needed.

Stopping the medication: Some people experience withdrawal effects if fluoxetine is suddenly stopped. Withdrawal symptoms may include headache, difficulty sleeping, numbness, tingling burning or prickling sensations, nervousness, anxiety, nausea, sweating or weakness. Before stopping the medication, talk to your doctor.

Suicidal or agitated behaviour: People taking this medication may feel agitated (restless, anxious, aggressive, emotional, and feeling not like themselves), or they may want to hurt themselves or others. If you experience these side effects or notice them in a family member who is taking this medication, contact your doctor immediately. You should be closely monitored by your doctor for emotional and behaviour changes while taking this medication.

Pregnancy: It has been reported that babies born to women who took similar medications during the last trimester of their pregnancy may experience adverse effects (such as breathing problems, seizures, trouble feeding, jitteriness, irritability, and constant crying). There may also be a slight increase in the risk of birth defects if fluoxetine is taken early during the pregnancy. This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately. Some babies whose mothers took fluoxetine during pregnancy have had withdrawal effects.

Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking fluoxetine, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children. The use of this medication by children and adolescents may cause behavioural and emotional changes, such as suicidal thoughts and behaviour.

What other drugs could interact with this medication?

There may be an interaction between fluoxetine and any of the following:

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

stop taking one of the medications,

change one of the medications to another,

change how you are taking one or both of the medications, or

leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.